The present invention mainly relates to a motor driving inverter for converting DC current from a DC power supply to AC current and supplying a motor-driven compressor of an air conditioner mounted on a motorcar with ac power.
Such type of motor driving inverter has a printed circuit board provided with a plurality of electronic components such as semiconductor switching devices with high current capacity, a microcontroller including an integrated circuit that is equipped with a central processing unit and on-off controls the semiconductor switching devices to produce three phase current, etc. The semiconductor switching devices generate a large quantity of heat because the motor driving inverter supplies a motor-driven compressor with heavy current. Therefore, each semiconductor switching device and each of the other electronic components such as integrated circuit devices that generate heat are provided with a radiator independently or, otherwise, the semiconductor switching devices and other electronic components such as integrated circuit devices that generate heat are cooled by a fan.
The motor driving inverter is provided with a metal box for accommodating the printed circuit board to shield the electronic components from electromagnetic noise from a number of noise sources in the motorcar and to shield electronic components in the motorcar from electromagnetic noise generated by the electronic components of the motor driving inverter.
In addition to the radiators or the fan, the motor driving inverter is provided with electromagnetic shields for shielding the microcontroller from electromagnetic noise generated by the semiconductor switching devices through which heavy currents are passed. Such shielding is required to prevent operation errors in the microcontroller.
The radiators or the fan, and the electromagnetic shields increase the size and the manufacturing cost of the motor driving inverter.
Therefore an object of the present invention is to provide a motor driving inverter for converting DC current from a DC power supply to AC current and supplying a motor-driven compressor of an air conditioner mounted on a motorcar with ac power which is compact and has high heat radiating capability.
Another object of the present invention is to provide a motor driving inverter for converting DC current from a DC power supply to AC current and supplying a motor-driven compressor of an air conditioner mounted on a motorcar with ac power which is compact and has high heat radiating capability, and whose microcontroller is shielded from electromagnetic noise from semiconductor switching devices thereof.
In accordance with the present invention, there is provided a motor driving inverter comprising a first printed circuit board provided with electronic components, a heat conduction plate made of a metal with high heat conductivity and adhered at one surface to the printed circuit board, thereby supporting the printed circuit board, a heat conduction member made of a material with high heat conductivity and connected to the heat conduction plate, thereby supporting the heat conduction plate, and a box made of a metal with high heat conductivity, accommodating the printed circuit board, the heat conduction plate and the heat conduction member, and connected to the heat conduction member, thereby supporting the heat conduction member.
In accordance with a preferred embodiment of the present invention, the heat conduction plate is adhered at the other surface to a second printed circuit board provided with an electronic component liable to be affected by electromagnetic noise, and the electronic components on the first printed circuit board are little affected by electromagnetic noise.
In accordance with another preferred embodiment of the present invention, the heat conduction plate is adhered at the other surface to a second printed circuit board provided with an electronic component liable to be affected by electromagnetic noise, and at least one of the electronic components on the first printed circuit board is liable to generate electromagnetic noise.
In accordance with another aspect of the present invention, there is provided a motor driving inverter comprising a printed circuit board provided with electronic components, a heat conduction plate made of a metal with high heat conductivity and adhered at one surface to the printed circuit board, and a box made of a metal with high heat conductivity and accommodating the printed circuit board and the heat conduction plate, wherein the heat conduction plate is fixed to the box with its the other surface abutting against the box.